Primary aldosteronism characterized by the overproduction of aldosterone by the adrenal glands, is sometimes accompanied by autonomous cortisol secretion. In this study, we retrospectively analyzed 8 cases of primary aldosteronism (PA) with subclinical Cushing’s syndrome (SCS). A total of 71 patients with PA underwent surgery at Jikei University Hospital from 2004 to 2013, and 8 of them were diagnosed with coexistent SCS. Four patients were male and four were female. The mean patient age was 56.9 years. One of the patients also had pheochromocytoma in the adrenal gland on the ipsilateral side. All patients had hypertension, 6 had hypokalemia, 5 had diabetes mellitus, and 3 had hyperlipidemia. All patients had autonomous cortisol secretion as shown in 1mg- or 8mg-dexamethasone suppression tests even though baseline cortisol levels were normal. Adrenal venous blood sampling with adrenocorticotropic hormone (ACTH) stimulation was performed on 5 patients, but the localization of PA could not be detected in 1 patient. Adrenocortical scintigraphy revealed suppression of the contra-lateral adrenal uptake in all 7 patients. Six patients including one patient who showed complete suppression of the contra-lateral adrenal uptake in adrenocortical scintigraphy, and 2 patients, whose ACTH levels were less than the detection limit, received postoperative steroid hormone replacement. In the literature, SCS co-existed in approximately 8. 6% of the patients with PA. In our study, SCS co-existed in approximately 11.3%. The degree of the autonomous secretion of cortisol varied with the patient, and some cases are accompanied by Cushing’s syndrome. Therefore, it is important to analyze the autonomous cortisol secretion even in patients with PA.